None.
Agree. I think the numbers are reasonable.
HOWEVER - I do have concerns for those that perhaps don't have an adult at home that can supervise their driving (or can afford a qualified instructor). There are some programs with volunteers (I can't even think of the name...).
I was fortunate enough when I was learning to drive that I had grandparents that supported me with my driving because Mum was working every day until late at night. For some, that luxury definitely isn't there and we have to recognise that. Again... the issue of $$$ comes into play when we start talking about instructors. Particularly those in low socioeconomic areas (which is how i've grown up so paying for an instructor wasn't practical).
I know I clocked up quite a number of hours doing a trip along the Hume to the NSW border (Albury/Wodonga) and back a few times. That was around 6-7 hours in total per trip there and back.
I guess the question we should be asking is: how can we support those 16-17 year olds on their learners permit that don't have a supervisor for either financial/lack of access reasons?